eli5, why can’t we have instant phone chargers?


Hey guys, I don’t understand enough about electronics to answer this, but if my electricity at home is able to power a washing machine.
Should it not be possible to have like a super battery that goes 100% instant, and then release normal current to the phone until it’s charged? More like an instant power bank?

In: 0

Batteries and other charging electronics are not 100% efficient, some of the energy becomes heat. This is why the phone gets hit when you charge them. So if you increase the charge current the result will be they get overheated.

There is another limiting factor too but heat is a major one.

A washing machine is not instantly changed, it uses electricity on demand. A phone can do that too, you just do not what to have them always plugged in.

It can be done but it would likely result in something expensive and not useful. The battery has to provide several key functions, it has to store energy, it has to convert (usually chemical energy) to electrical energy and it has to do this in reverse when charging.

On top of that it needs to have several characteristics, reasonably small lightweight, safe, reliable, long lasting, cost effective and sufficiently energy dense.

Putting all these characteristics into a single product isn’t easy. The first problem with “instant” phone charge is safety. Anything that can take in energy quickly also puts out energy quickly. And this results in heat and rather fiery and explosive characteristics. If more safety devices were incorporated (shielding, armor plating, safety circuits etc) it becomes a very expensive and heavy/bulky product.

This is why EV batteries have to be operated with all these things built in to handle the energy density and power.

to make an analogy a firehose can put put an immense amount of water, but this doesn’t mean you can drink straight from it all the water you need in a second

this is because people are more delicate than wood and concrete and can only take so much water at once

similarly batteries and electronic circuits are mode delicate than a big fat heater and you can’t shove a few kilowatts in there, it’s gonna overheat and explode

We have those, they’re called capacitors. They don’t store a lot of power in small spaces, so your phone becomes big again.

People don’t want big phones so we have to use lithium type batteries which do not like to be charged quickly – they become quite hot.

Research is ongoing into finding capacitors that store energy densely (called super caps, don’t confuse them with snake oil laced “super caps” with Lithium Titanate Oxide or LTO batteries)

Research is also ongoing into making lithium batteries charge faster, that’s why we have batteries today that charge much faster than a few years ago.

Why should it be possible?

There’s no energy storage in the world that is instant, batteries are no different. A flywheel takes time to get up to speed. A water reservoir needs time to fill up.

Batteries work by having chemical processes that release electrons happen in a controlled fashion. Rechargeable batteries are the same, but use chemicals whose processes can be reversed.

These processes take time, and are inefficient. You don’t get all the electricity put into them back as usable power. The power lost turns into heat, and too much heat in too short a time can lead to fires.

Even without the fire hazard, trying to force a chemical reaction to happen faster than it wants to is likely to just change the chemical properties in such a way that they’re no longer usable.

Imagine trying to make a hot dog. Grilling it takes maybe 5 minutes. Could you do it in 0.1 seconds if you just had a flame that was 30000 degrees instead of 1000 degrees? No, you’d get a coal shell with a raw hotdog inside. You don’t get the chemical reaction you want if you don’t supply the right amount of energy at the right rate.